This invention relates to the construction of and the method of making scissors. The great majority of scissors commercially available today are the hot forged type. These scissors are generally rather expensive for the following reasons:
1. Forging dies are expensive to make and have a relatively short life. The high temperatures and pressures wear them out quickly. They can be dressed up a few times but then must be discarded. Only highly skilled (and highly paid) die makers can make new ones.
2. Forging equipment is expensive. Because of the high pressures required, the presses must be very large. Several hits are necessary to make a forging and then it must be trimmed. All this requires a number of machines and associated handling equipment.
3. Forging labor is high. For most products such as scissors, the process is still manual or at best, semi-automatic. There often are intermediate steps such as shearing bars to length, heating bars prior to hitting, annealing, and the like. Because of the difficult working conditions and skill required, the workmen usually are highly paid.
4. Grinding is extensive. Forging leaves a coating of scale and a very rough finish. For the most part, this has to be ground off as do other surfaces and edges. Since the shape of scissors is irregular, grinding does not lend itself to automation. The many sides, edges, curves, etc. generally have to be done manually in a number of separate steps.
5. This extensive grinding requires a high cost of grinding material and equipment.
6. Much polishing also is required. In order to prepare the scissors for plating, all ground and unground surfaces have to be carefully polished. Polishihg is very time-consuming, especially around the handle area. As with grinding, there is a substantial cost of material and equipment. It also is a manual operation.
7. Utilities cost is substantial. Heating the bar stock and the electricity required to run the large presses plus many grinders, polishers, etc. involves a significant utility cost per unit. Another important cost is the high percent of steel waste. Probably less than fifty percent of the bar stock actually is used for the final scissors because of its shape. The waste has a very low value compared to original steel cost.
For the foregoing reasons, most of the forged scissors are manufactured in low labor cost countries foreign to the United States.
Other methods presently used for scissor manufacturing generally produce the final shape of the scissors first and then follow up with the steps of grinding, polishing, plating and assembly. One such method is that of casting. However, the casting procedure is much inferior in quality to the forged scissors. Its granular micro-structure is a poor one for a cutting edge. The edges wear relatively quickly because of the granular, less dense material. Being cast, the scissors cannot flex during cutting action as do forged or some other type scissors. This results in a stiff, hard to close tool. Althought less expensive than forging, casting does require much labor and, therefore, is done primarily in low labor cost countries. Cast scissors generally are heavy because more weight is necessary to offset the low strength.
Other than hot forging, the most popular method is cold forging and stamping. Cold forging is very similar to plain stamping except that the upper surface from point to pivot is coined or smashed to give the traditional forged appearance. Otherwise, cold forging and stamping are the same in that both involve punching the shape out of a thin, flat length of sheet metal. The process can be an automatic one and thus the labor is low. A disadvantage, however, is that the handle usually is the same thickness as the blade since it is all punched out of the same sheet. This makes for an uncomfortable pressure on the fingers during cutting. The main disadvantage is that, like forgings and castings, these types of scissors cannot be ground and polished automatically. For this reason, producers of these scissors generally do not grind any more than absolutely necessary and do very little polishing at all. The percentage of waste material is not as high as in forging but, because of the shape of the scissors is a poor one for nesting in the blank, the waste probably runs as high as forty percent. Another bad feature is the fact that these scissors usually are of lower carbon than the level required for good cutlery type edges. High carbon steel is very difficult to cold forge. It also is very difficult to punch a shape such as scissors out of high carbon steel. Producers usually use lower carbon grades in order to extend tooling and equipment life.